One way to fix the player distribution between campaigns and to generate new interest in PvP is to create a second Cyrodiil map. The current map is Cyrodiil circa 2E 583. If ZOS creates a second map, say circa 2E 587, with keeps in different locations, new daily quests, and some other minor changes, you will see players wanting to try the campaigns with the new map, while others staying in the old map campaigns.
BTW...Another way to generate interest is to tell people what is not obvious about PvP. It has a very steep learning curve compared to PvE, and until you learn what to do and when, it won't be quite as fun.
EDIT: This idea is for down the road. I believe the higher priority in Cyrodiil is fixing the latency and bugs.
Edited by ghengis_dhan on September 27, 2014 11:41PM "It is not the critic who counts: not the man who points out how the strong man stumbles or where the doer of deeds could have done better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly, who errs and comes up short again and again, because there is no effort without error or shortcoming, but who knows the great enthusiasms, the great devotions, who spends himself for a worthy cause; who, at the best, knows, in the end, the triumph of high achievement, and who, at the worst, if he fails, at least he fails while daring greatly, so that his place shall never be with those cold and timid souls who knew neither victory nor defeat."
Teddy Roosevelt, Paris, 1910